I would recommend writing tests specifically for testing the PostgreSql changes, ideally you can write them purely in PostgreSql, maintaining a nice separation

I would recommend writing tests specifically for testing the PostgreSql changes, ideally you can write them purely in PostgreSql, maintaining a nice separation of your code and your SQL. Also, the only thing that should really need proper testing are stored procedures, your check constraints can't possible be so complicated that they warrant tests. The unit tests that test out your business logic should use mock data - it's just much more reliable, reproducible, and faster.